Sustainably reinforced polymers are of interest in numerous industries ranging from industrial, automobile, medical, and other applications. These reinforced materials often have superior strength-to-weight and stiffness-to-weight ratios and have a wide range of physical, thermal, and electrical characteristics that make them ideal for product creation.
Composite thermoplastics can offer increased strength, decreased density and numerous other beneficial characteristics over traditional plastics. Companies are searching for biodegradable polymers and composites because they are becoming more aware of environmental and waste management issues, decreasing fossil fuel resources, and rising oil prices (Bergert 2011). The design and production of sustainable composite materials is occurring in industries ranging from the construction industry to the packing industry. Being more ecofriendly is also becoming an important requirement for consumers. In addition, alternative renewable carbon sources are being explored to promote the eco-friendly trend in addition to finding any superior properties of the alternative carbon sources.
The inclusion of certain types of nanoparticles in polymer composites, in addition to altering mechanical and physical properties, can also cause the composites to be conductive or capacitive in nature, or enhance a polymer's natural conductivity (Lu and Xu 1997; Gao et al. 2010; Jiang et al. 2006; Yan and Jeong 2017). This technological advance in polymer chemistry has inspired significant research into energy storage and energy management applications. The inclusion of carbon-based fillers, such as graphene (Potts et al. 2011; Kim et al. 2011) and carbon nanotubes (CNT) (Ma et al. 2010; Manchado et al. 2005; Coleman, Khan, and Gun'ko 2006) have been shown to improve the mechanical, thermal, and electrical properties of polymer composites. Flexible polymer composites with a high dielectric permittivity (high-k values) have attracted attention for their possible applications in high-performance electronics, wearable devices, and smart fabrics. An increase in the dielectric permittivity leads to larger energy densities which can be utilized for energy storage (Bikky et al., 2010).
Hemp has a long history of industrial use and was widely cultivated in the world for its rough use for the fiber portion of the plant. Hemp has many advantages over other agricultural crops, namely, the plant itself is resilient to weeds, it can be harvested 2-3 times a year and it does not need pesticides or herbicides to flourish. Its deep root system means that hemp plants need much less nitrogen (fertilizer) and water to flourish compared to other crops like cotton. Moreover, farmers can use hemp plants as an alternative to clear fields for other crops. For example, the average hemp plant grows to a height of between six (6) feet to sixteen (16) feet and matures in approximately seventy (70) to one hundred ten (110) days, thus facilitating multiple harvest opportunities each year in many areas of the world. A hemp crop has the potential of yielding 3-8 tons of dry stalks per acre per harvest while remaining carbon negative.
Hemp, like many dicotyledonous plants, contains a phloem (hurd) and fibers (bast fibers) around the phloem. Inside the bast fiber is the hurd, a wood-like portion of the hemp plant, which surrounds a hollow core. In any given hemp plant, there is significantly more hurd biomass than of fibers. Unfortunately, the use of the hurd has been shunned to date, even though it is the primary biomass of the plant. Manipulation and use of the hurd, therefore, would serve as a critical step in use of this cellulosic product that would otherwise become waste.
Fibers have been frequently utilized individually, which requires that the fibers are separated from the hurd by mechanical (for example, decortication), or chemical properties, and the fibers can then be used for any fiber materials, including textiles like carpet, yarn, rope, netting, matting, and the like, but hurd has low use throughout the world.
Widespread use of cannabis was dramatically reduced during the 20th century due to the concern regarding the amounts of tetrahydro cannabinoids (THC) within the plants. However, there are a number of different strains/cultivars of the hemp plant that contain smaller and larger amounts of the psychoactive compound, THC, and thus cultivation can be optimized for the particular growth and THC content that is desired, including plants with low to zero THC. Here, a fast growth rate and a high total biomass is desired, although any biomass may be suitable for use. These traits may be naturally derived through strains and cross-breeding as known to those of ordinary skill in the art, or genetically modified
Ultimately, hemp functions as a carbon negative plant, making it highly attractive for large scale use, especially where a downstream use can be identified. These features make hemp an intriguing option for cultivation, but the many difficulties with the plant have precluded its use on any scale up to this point.
Therefore, in an effort to pursue sustainable and environmentally responsible composite filler material, suitable for use in a variety of master batch processes, and as a replacement for the more expensive and time/process intensive CNTs (carbon nano tubule) and graphenes in any number of composite materials, applicant has identified nanoparticle hemp-based materials optimal for a feedstock for nanocomposite production. Herein, we describe materials, methods, and processes for generating novel nanocomposite materials using hemp as a nano or micro particle within a composite material.